A gas mixture consists of 2 moles of oxygen and 4 moles of argon at temperature T. Neglecting all vibrational modes, the total internal energy of the system is

Options

A. `4RT`
B. `15RT`
C. `9RT`
D. `11RT`

Answer

D

Explanation

The internal energy of `n` moles of a gas is `u=(1)/(2)nFRT`
where `F=`number of degrees of freedom.
The internal energy of `2` moles of oxygen at temperature `T` is
`u_(1)=(1)/(2)xx2xx5RT=5RT` , (`F=5` for oxygen molecule)
Total internal energy `=u_(1)+u_(2)=11RT`